Ricki Lake: 'I Can't Believe I Was Fat'

Ricki Lake has trimmed 140 lbs. from her all-time top weight
of 270 lbs. – and says she is holding steady.

"I can't believe I was a fat person for most of my life," the former talk show host, rocking a sexy black Herve Leger dress (size small), told PEOPLE at a recent benefit for the New Space for
Women's Health, a New York City birthing center slated to open in 2010.

"I didn't have surgery and I worked hard. There's no secret. I'm active. I watch what I eat," Lake, 40, adds.

But she's certainly not immune to the pressure to stay thin. "According to Hollywood standards, I'm not a thin girl. I’m a normal girl," says the mom of two boys, Milo, 11, and Owen, 7. "I don't want to perpetuate that obsession but yet
I am also guilty of wanting ... to lose weight."

"I'm just grateful that I have sons and not daughters because it's that much harder," she says.

Lake sticks to meals delivered by a service called Fresh Dining ("It's organic, it's fresh, and I still love it," she says) but admits unpredictable factors in life could one day interfere.

"With the weight stuff I don't have any answers," she says. "Something tragic in my life could happen and I could balloon and gain weight. I can't promise I will be like this forever."

And with the holidays in full swing? "I will be
really conscious because I have this book coming out and I want to look
great," she says. "I don’t need to lose anymore weight. [But] I don’t want to go backwards. So
I'm not going to pig out this Christmas."